Logging Tool Enables Fracture Characterization for Enhanced Field Recovery

摘要

ExxonMobil has developed a fracture mapping tool that usesrnacoustic methods to infer the geometry of induced hydraulicrnfractures. This tool may be run in the treatment well duringrnfracturing, or it can be used in one or more offset monitoringrnwells. This tool, "TABS" for Triaxial Borehole Seismic,rnconsists of an array of three triaxial geophone receivers, arntelemetry sub to transmit the data to surface in real time onrnconventional 7-strand wireline, and an interface to a Gyrodatarnsurvey tool to provide the tool orientation when clamped. Therntool subs are interconnected with "flex links" that are rigid inrnrotation but flexible in bending to allow each clamp arm tornmake independent coupling to the wellbore casing. Thernoverall design is that of a logging tool, facilitating applicationrnvia wellhead lubricators.rnThe geometry of the stimulated fracture has a significantrnimpact on well productivity and recovery. In manyrnapplications, the reservoir depletion pattern is highlyrndependent on this geometry. Some key interactions betweenrnproductivity and fracture geometry include:rn· Well spacing is determined by the fracture length,rnformation properties, and depletion plan.rn· Within this spacing constraint, well locations arerndetermined by the induced fracture azimuth. Wells arernplaced to reduce interference among producers and tornmaximize conformance.rn· Fracture height growth out of zone may lead to morerncostly stimulation treatments and lower well productivity.rnModifications to the treatment design and adjustments tornthe selection of perforated intervals may increase wellrnperformance.rnWorking with the ExxonMobil Production Company, thernTABS tool has been used to monitor 32 fracture treatments inrn16 well entries. Results from several of these fieldrnapplications will be used to describe the TABS technology andrnto demonstrate fracture geometry measurements.